ELASTIC PROJECTILE PROPULSION SYSTEMS AND METHODS
An elastic projectile propulsion system deploys a plurality of springs that bias a common launching cord via a plurality of block and tackle pulleys. Each sheave of the pulley is coupled to the moveable end of a spring such that the force of each spring contributes to the energy imparted to a projectile by the launching cord without adding significant friction or inertial resistance.
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This application claims the benefit of U.S. Provisional Application No. 61/867,383, entitled ELASTIC PROJECTILE PROPULSION SYSTEM, filed on Aug. 19, 2013, and 61/946,736, entitled ELASTIC PROJECTIVE PROPULSION SYSTEM, filed Mar. 1, 2014, which applications are incorporated herein by reference.
BACKGROUNDThe present disclosure relates to a compact propulsion systems that deploys stored elastic energy to propel a projectile, and more particularly to a compact propulsion system for launching an arrow and other flying projectiles.
Prior methods of launching arrows and other projectiles have deployed elastic energy stored in springs, such as leaf springs in a bow, torsion springs and coil springs, rubber tubes and bands, as well as the elastic energy stored in a stretched launching cord. Various combinations of these elements are known, some of which include a series of pulleys to extend and direct the launching cord in a generally serpentine path. See, for example, U.S. Pat. No. 2,515,205 A to Fieux for Catapult Device for Launching Aerial Machines, issued Jul. 18, 1950.
However, the prior systems have limitations. While metal springs are more reliable over a range of temperatures than rubber springs, the higher mass of the metal springs imposes a velocity limitation.
Bow systems are not compact (typically having a width of at least 12 inches (30.48 centimeters) or more at a widest point), and require large loading force (crossbows typically having 125-200 lbs (56.7-90.72 kilograms) of draw weight), which is overcome by adding heavy, bulky and complicated levers and ratchets, thereby increasing size and weight of the device.
Additionally, bow systems are limited in the ability to reabsorb stored energy without sustaining damage to the bow during launch. Hence, bow systems require a minimum arrow weight be matched proportionately to a draw force of a bow in order to dissipate energy away from the bow during launch and ensure functionality without incurring damage to the bow system. Widely adopted industry standards recommend that a bow never be deployed to launch without an arrow (“dry fired”) and have set a minimum ratio of arrow weight to draw force which, in turn, imposes a velocity limitation.
The devices disclosed herein provide a propulsion configuration that can overcome the above limitations.
SUMMARYAn aspect of the disclosure provides a propulsion device comprising a rigid elongated barrel member having a forward (distal) launching end and an opposing (proximal) stock connecting end, a pair of forward (distal) spring members each mounted to connect at a distal end thereof on opposing sides of the barrel adjacent the forward (distal) launching end, each forward (distal) spring having a distal end connected to the barrel opposite the moveable proximal end, a pair of rear (proximal) spring members, each mounted to connect to the barrel at a proximal end thereof on opposite sides of the barrel adjacent the proximal stock end, a pair of moveable fore pulley blocks, each coupled to the proximal moveable end of each forward spring member and at least one proximal moveable pulley block, connected to the distal moveable end of each rear spring member, a launching cord having each of the opposing ends and engaging both the distal and proximal moveable pulley blocks on opposing sides of the barrel to provide a pair of moveable, counter acting block and tackle pulleys to couple the elastic energy stored in the distal and proximal spring members when a launch cord center is drawn in a proximal direction toward the stock connecting end of the barrel. Components made from elastic materials are resilient and enable the component to spring back into a predetermined shape after a deforming force is removed.
A second aspect of the disclosure provides a method of propelling a projectile, such as an arrow. The method comprises the steps of providing a propulsion device, providing a projectile having a forward (distal) end and a rear (proximal) end opposite the forward end, resting the projectile on a barrel to engage a center of a launching cord at the rear (proximal) end of the projectile, drawing the center of the cord and attached projectile in the rearward (proximal) direction to tension the launching cords engaged in the adjacent moveable pulley blocks attached to the distal and proximal spring members on both opposing sides of the barrel and in turn extend each of the distal and proximal spring members toward the other, releasing the launching cord and projectile to provide a mutual and simultaneous transfer of energy from the tensioned springs and launching cord to the projectile. Alternatively, the linear projectile, such as an arrow, may be secured within the device after the launch cord has been fully tensioned, and thereafter, the user releases the draw on the projectile (e.g., by pulling the trigger, releasing the launch cord, etc.), which causes a transfer of energy from the tensioned springs and launch cord to the projectile.
An aspect of the disclosure is directed to propulsion devices. Suitable propulsion devices, comprise: a) an elongated barrel member forming a cavity having an elongated barrel member proximal end and an elongated barrel member distal end, where the elongated barrel member proximal end engages a mounting stock, b) a pair of forward spring members each having a forward spring member proximal end and a forward spring member distal end, the pair of forward spring members positioned within the cavity of the elongated barrel member wherein the distal ends of the forward spring members connect to a corresponding moveable brace and the proximal ends of the forward spring members connect to a moveable pulley blocks, c) a pair of rearward spring members, each having a rearward spring member proximal end and a rearward spring member distal end, the pair of rearward spring members positioned within the cavity of the elongated barrel member wherein the distal end of the rearward spring members connects to the moveable pulley blocks and the proximal ends of the rearward spring members connects to the corresponding moveable braces, d) at least one pair of forward pulleys, each forward pulley coupled to the forward spring member proximal ends and at least one rearward pulley, connected to each of the rearward spring member distal ends, and e) a launching cord having a first end and a second end which can attach at either the forward moveable pulley blocks or the rearward moveable pulley blocks and traverse a serpentine path around pulleys to engage both the forward pulleys and rearward pulleys. In at least some configurations, the pair of forward pulleys and the rearward pulley are configurable to comprise a counteracting block and tackle pulley which couples an elastic energy stored in the forward spring members and the rearward spring members when the launch cord is drawn rearward toward the stock connecting end of the barrel. Additionally, a rail can be provided and interiorly positioned in the barrel member. The rail can also be configurable to vertically move while remaining stationary horizontally. Additionally, a cocking mechanism and/or trigger assembly can be provided. Propulsion devices are configurable such that they have a width of 12 inches or less. In some configurations, the launching cord is wrapped three or more times around the distal pulley. Additionally, the forward spring members and the rearward spring members are combined in parallel banks, wherein each bank engages one or more moveably pulley blocks.
Another aspect of the disclosure is directed to linear archery systems. The linear archery systems comprise: a) an elongated barrel member forming a cavity having an elongated barrel member proximal end and an elongated barrel member distal end, where the elongated barrel member proximal end engages a mounting stock, b) one or more of a forward spring member each of the one or more forward spring members having a forward spring member proximal end and a forward spring member distal end, the one or more forward spring members positioned within the cavity of the elongated barrel member wherein the distal end of the one or more forward spring members connects to a moveable brace and the proximal ends of the forward spring members connect to a moveable pulley block, c) one or more rearward spring members, each of the one or more rearward spring members having a rearward spring member proximal end and a rearward spring member distal end, the one or more rearward spring members positioned within the cavity of the elongated barrel member wherein the distal end of the one or more rearward spring members connects to the moveable pulley blocks and the proximal ends of the rearward spring members connects to the corresponding moveable brace, d) one or more forward pulleys, each of the one or more forward pulleys coupled to at least one of the one or more forward spring member proximal ends and at least one rearward pulley, connected to the rearward spring member distal end, and e) a launching cord having a first end and a second end which can attach at either the forward moveable pulley blocks or the rearward moveable pulley blocks and traverse a serpentine path around pulleys to engage both the forward pulleys and rearward pulleys. In at least some configurations, the pair of forward pulleys and the rearward pulley are configurable to comprise a counteracting block and tackle pulley which couples an elastic energy stored in the forward spring members and the rearward spring members when the launch cord is drawn rearward toward the stock connecting end of the barrel. Additionally, a rail can be provided that is interiorly positioned in the barrel member. The rail is also configurable to vertically move while remaining stationary horizontally. Additionally, a cocking mechanism and/or trigger assembly can be provided. Configurations of the systems have a width of 12 inches or less. Additionally, the launching cord is wrapped three or more times around the distal pulley.
Still another aspect of the disclosure is directed to self-arresting propulsion systems. The self-arresting propulsion systems comprise: a) an elongated barrel member forming a cavity having an elongated barrel member proximal end and an elongated barrel member distal end, where the elongated barrel member proximal end engages a mounting stock, b) a pair of forward spring members each having a forward spring member proximal end and a forward spring member distal end, the pair of forward spring members positioned within the cavity of the elongated barrel member wherein the distal end of the forward spring members connect to a corresponding moveable brace and the proximal ends of the forward spring members connect to a moveable pulley block, c) a pair of rearward spring members, each having a rearward spring member proximal end and a rearward spring member distal end, the pair of rearward spring members positioned within the cavity of the elongated barrel member wherein the distal end of the rearward spring members connect to the moveable pulley block and the proximal end of the rearward spring members connects to the corresponding moveable brace, d) a pair of forward pulleys, each forward pulley coupled to one of the forward spring member proximal ends and at least one rearward pulley, connected to the rear ward spring member distal end, and e) a launching cord having a first end and a second end which can attach at either the forward moveable pulley blocks or the rearward moveable pulley blocks and traverse a serpentine path around pulleys to engage both the forward pulleys and rearward pulleys, wherein the pair of forward pulleys and the rearward pulley comprise a counteracting block and tackle pulley which couples an elastic energy stored in the forward spring members and the rearward spring members when the launch cord is drawn rearward toward the stock connecting end of the barrel. Additionally, a rail interiorly positioned in the barrel member can be provided. The rail can be configurable to vertically move while remaining stationary horizontally. Some configurations will include a cocking mechanism and/or trigger assembly. As with other configurations, the systems have a width of 12 inches or less. The launching cord is wrapped three or more times around the distal pulley.
Yet another aspect of the disclosure is directed to methods of operating a system according to any of the configurations disclosed. The methods comprise the steps of: providing a propulsion device, drawing the launching cord in the rearward direction to tension the launching cord and extend each of the forward spring member and rearward spring members towards each other, and releasing the launching cord to provide a mutual and simultaneous transfer of energy from the tensioned springs and launching cord. Additionally, the method can include providing a linear projectile, and placing the linear projectile in the barrel of the propulsion system to engage the launching cord, wherein the steps of providing the linear projectile and placing the linear projectile in the barrel of the propulsion system is performed after the step of drawing the launching cord.
INCORPORATION BY REFERENCEAll publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference, for all purposes and as if repeated in total in the present application. Additional references of interest include U.S. Pat. No. 4,050,438A to Pfotenhauer issued Sep. 27, 1977 for SPRING TYPE PROJECTING DEVICE; U.S. Pat. No. 4,169,456A to Van House issued Oct. 2, 1979 for SHORT LIMB ARCHERY BOW; U.S. Pat. No. 4,411,248A to Kiveson issued Oct. 25, 1983 for CATAPULT CONSTRUCTION; U.S. Pat. No. 4,703,744A to Taylor et al. issued Nov. 3, 1987 for APPARATUS FOR SHOOTING A PROJECTILE; U.S. Pat. No. 5,243,955A to Farless issued Sep. 14, 1993 for MECHANICAL SHOOTING APPARATUS; U.S. Pat. No. 5,673,677A to Wing issued Oct. 7, 1997, for PROJECTILE LAUNCHING APPARATUS; U.S. Pat. No. 7,578,289B2 to Norkus issued Aug. 25, 2009 for COMPOUND ARCHERY BOW WITH EXTENDED INVERTED STROKE; and PCT Publication WO2012/150387A1 to Lamine published Nov. 8, 2012 for SPEARGUN FOR UNDERWATER FISHING.
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
Referring to
The various described embodiments described herein provide multiple benefits, which include for example, stable elastic metal or composite springs which are deployable with a reduced inertial burden imposed by the spring mass on the velocity of the projectile such as an arrow, as the elastic projectile propulsion system 100 couples the force and travel distance of multiple springs utilizing moveable pulleys and an attached launch cord to simultaneously accelerate the launch cord and attached projectile at a velocity that exceeds the velocity of each individual spring moving simultaneously within the system. In addition, the elastic projectile propulsion system 100, which is a launching device, can be very narrow (e.g. 12 inches (30.48 centimeters) or less in width), light-weight (e.g., 9 pounds (4.08 kg) or less in weight), compact (e.g., having a volume of 500 cubic inches (8,193 cubic centimeters), or less). As an example of this benefit, in the comparison to competitive shooting crossbows, a high velocity arrow flight is achieved without a bulky, wide and heavy bow limbs. As well, the stable metal or composite springs within the elastic propulsion system 100 provide more reliable elastic performance under a range of temperate weather conditions compared to propulsion devices utilizing rubber elasticity, which is known to have elastic performance that varies with a wide range of temperate weather conditions.
Additionally, the embodiments described provide for a self-arresting propulsion system which allows the safe use of lighter weight arrows than usable in currently available bows and crossbows, which generally follow industry guidelines that limit arrow weight to 5 grains of arrow weight per pound of bow draw force. As will be appreciated by those skilled in the art, lighter arrows can attain much higher velocities than heavier arrows when launched at the same draw length and force (e.g., power stroke). The propulsion system 100 is capable of safely launching projectiles such as arrows that are less than 5 grains of arrow weight per pound of draw force. Still another advantage to the configurations provided herein is that there is very low draw weight, which is less than 125 lbs. This enables the user to directly cock the device and does not require a cocking device employing significant mechanical advantage. As will be appreciated by those skilled in the art, most crossbows range from 125-200 lbs (56.7-90.72 kilograms) of draw weight and require a cocking assist either as a separate device or as an integrated component in order to gain a mechanical advantage.
Devices and SystemsTurning now to
Elongated center rail member 110 and fixed braces 220, 230 can be formed integrally with elongated outer frame 111 in a fixed position to form a rigid and robust barrel structure or housing. A pair of forward spring members 120, 120′ positioned distally, are mountable to connect to a fixed brace 220 via moveable braces 127a, 127′a at a distal spring end 120a, 120′a thereof on opposing sides of the elongated center rail member 110 adjacent a distally positioned forward launching end 110a, each of the forward spring members 120, 120′ having a proximal spring ends 120b, 120′b opposite the distal spring ends 120a, 120′a. Likewise, a pair of rear spring members 130, 130′ positioned proximally, are mountable to connect to fixed brace 230 via moveable brace 137a, 137′a at proximal spring ends 130a, 130′a thereof on opposite sides of the elongated center rail member 110 adjacent the proximally positioned opposing mounting stock 160 connecting end 110b, with distal spring ends 130b, 130′b opposite the proximal spring ends 130a, 130′a. Each of the forward spring members 120, 120′ and the rear spring members 130, 130′ is connectable to a member of a moveable pulley block or block and tackle system 140 (shown in more detail in
For a handheld device, as shown in
Coupling each moveable pulley block and an associated pulley(s) to move with a spring overcomes an inertial burden of metal springs by adding a force of multiple cooperating springs without excess friction. Moreover, it is preferable to provide three wraps of a launch cord 150 between distal pulleys 126a, 126b, and proximal pulley 136 and three wraps of launch cord 150 between proximal pulley 126′a, 126′b and proximal pulley 136′, as illustrated in
The combination of multiple launch cord wraps between pulleys that move in cooperation with the springs on release of the launch cord and the projectile enables a large launch velocity by simultaneously improving the speed at which the force of the launch stroke is transferred to the projectile and facilitates a compact, light-weight, robust and reliable design. First, it should be understood that the launch velocity will be proportional to the product of the launching force and launch stroke, which is the distance over which the force is applied. Second, it should now be understood that the velocity will also be proportional to the speed at which the launching force can be applied. However, coil springs have not been favored for archery propulsion by those skilled in the art because coil springs have been at a compromise between these factors, as increasing the launch force and or stroke through larger or more powerful springs is limited by proportional increase in spring mass and inertia. Although elastomers or rubber materials provide a high energy to mass density, the materials are not reliable below 40° F. (4.4 degree Celsius). Further, the materials can degrade or crack from repeated use and environmental exposure, and are subject to physical damage from other materials they may contact. Metal and composite coil springs are generally more reliable than elastomers or rubber materials when used in these conditions.
Multiple parallel springs can be employed to engage each distal moveable pulley blocks 125, 125′ or proximal moveable pulley blocks 135, 135′, as shown in
As illustrated in
As shown in
As shown in
As discussed with respect to
Further, to the extent some launching devices deploy metal or other torsion springs that work to displace a pulley that directs a launch cord, their performance can likely be improved by adding a second moveable pulley or moveable pulley block connected to a compression or tension spring to wrap the launch cord back to the torsion spring member before it engages the projectile.
Additionally, moveable braces 127a, 127′a and moveable brace 137a, 137′a can be used to allow free travel through fixed braces 220, 230, respectively, which are firmly attached to the inner walls at opposing ends of elongated outer frame 111 and elongated center rail 110. One or more bumpers 128, 128′, are mounted to the distal ends of moveable braces 127a, 127′a located on the distal face of fixed brace 220, and bumpers 138, 138′ mounted to proximal ends of moveable brace 137a, 137′a located on the proximal face of fixed brace 230, as illustrated in
Comparative test results revealed that the configuration illustrated in
In another configuration a launch cord release latch 170, 170′ as shown in
The trigger assembly 185 is configured to attach to the mounting stock 160 via a latch hook 181 installed into the trigger assembly 185. The latch hook 181 interfaces with a corresponding stationary latch pin 162 that is located in the lower portion of the mounting stock 160, as shown in
The moveable pulley blocks are attachable to either the distal or proximal spring members that deploy a plurality of pulleys be configured such that each pulley in the block rotate independently of the others.
However, alternatively, each wrap of the launching cord can connect multiple pulleys that are attached to the spring ends, each moveable pulley block having a single pulley.
Methods include operation of the devices disclosed above. In practice, a user obtains a linear projectile, such as an arrow, mounts the projectile in the barrel of the device to engage the launch cord. Once the projectile is secured within the device, the user draws the projectile in a rearward direction to tension the launch cords and extend each of the forward springs and rearward springs. Thereafter, the user releases the draw on the projectile (e.g., by pulling the trigger, releasing the launch cord, etc.), which causes a transfer of energy from the tensioned springs and launch cord to the projectile. Alternatively, the linear projectile, such as an arrow, may be secured within the device after the launch cord has been fully tensioned, and thereafter, the user releases the draw on the projectile (e.g., by pulling the trigger, releasing the launch cord, etc.), which causes a transfer of energy from the tensioned springs and launch cord to the projectile.
TestingVarious configurations of the propulsion mechanism were tested to determine superior arrow velocity, as illustrated in
As shown in
The embodiment of
1) 197 ft/sec (6005 centimeters/second),
2) 199 ft/sec (6066 centimeters/second),
3) 196 ft/sec (5974 centimeters/second).
Variances in velocity were likely due to minor adjustments made to the arrow rest between each test.
The propulsion mechanism was also configured as shown in
While the highest velocities achieved during tests peaked at 339 ft/sec (1.033e+004 centimeters/second) utilizing a 270 grain arrow at 30 inch (76.2 centimeters) draw length and 78 lbs (35.38 kilograms) draw force, it was discovered that some energy was lost in the launch cord 150 being stretched. It is assumed that solely utilizing a more robust launch cord 150 will result in greater velocities.
As well, it was discovered after velocity testing concluded that utilizing the same spring wire and outer diameter design with a slight increase in spring length resulted in the ability to generate equal or more energy in the power stroke with a significant decrease in draw length. For example, the same spring design used in all the tests was increased in length by 0.9″ and resulted in the ability to decrease the draw length by 6″ while generating a ˜2% increase in power stroke foot-pounds, all with the same 78 lbs (35.38 kilograms) draw force. This was achieved by increasing the initial tension in the springs via tightening of the launch cord which increased the total amount of force that was distributed over the length of the shortened draw stroke. It was also realized that the addition of more pulleys and resulting increase in pulley ratio would allow the use of shorter, more powerful springs to distribute their force over similar or greater draw lengths. It is reasonable to believe that future tests are likely to reveal increases in arrow speeds as shorter, lighter arrows matched to the reduced draw length, with a slight increase in power stroke force will result in more velocity. As well, overall device length can be reduced by a shorter draw length, consistent with a more compact and maneuverable design.
Testing of the shock absorbing system described above was conducted to assess damage caused to the entire system including the elastic projectile propulsion system 100 as a result of launching a projectile such as an arrow 10 not meeting minimum current standards of weight to draw force ratio. The commonly followed industry standard, set and maintained by the International Bowhunting Organization (IBO), is prescribed in a ratio that states an arrow typically weighs at least 5 grains per every one pound of draw force (for bows generating arrow velocities above 290 feet per second (8839 centimeters/second)). Testing was performed with arrows weighing a little as 270 grains (30″ in length) at a draw force of 78 pounds (35.38 kilograms), resulting in a testing ratio of approximately 3.5 grains per one pound of draw force (generating arrow speeds significantly above 290 feet per second (8839 centimeters/second)). Though testing was not conducted to the point of failure, repeated launches did not result in any observed damage to the elastic projectile propulsion system 100. While dry fire tests (without an arrow) were not performed, it is believed that parameters of the described shock absorbing system are capable of being adjusted to achieve dry fire without damage to the elastic projectile propulsion system 100. The demonstrated ability of the propulsion system 100 to reabsorb stored energy not imparted to the arrow upon release and thus launch lighter arrows at equal draw forces compared to conventional bow systems provides an advantage in the ability to increase arrow velocity without increasing draw force or causing corresponding damage to the system.
While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
Claims
1. A propulsion device, comprising:
- a forward spring member having a forward spring member proximal end and a forward spring member distal end, wherein the distal end of the forward spring member connects to a first brace and the proximal end of the forward spring member connects to a distal moveable pulley block,
- a rearward spring member having a rearward spring member proximal end and a rearward spring member distal end, wherein the distal end of the rearward spring member connects to a proximal moveable pulley block and the proximal end of the rearward spring member connects to a second brace,
- at least one forward pulley coupled to the forward spring member proximal end and at least one rearward pulley connected to the rearward spring member distal end, and
- a launching cord engaging the forward pulley and the rearward pulley.
2. The propulsion system of claim 1, wherein the at least one forward pulley and the at least one rearward pulley comprise a counteracting block and tackle pulley assembly which couples an elastic energy stored in the forward spring member and the rearward spring member when the launch cord is drawn rearward.
3. The propulsion device of claim 1, further comprising a rail with a distal fixed brace at a distal end thereof and a proximal fixed brace at a proximal end thereof, the distal fixed brace supporting the first moveable brace and the proximal fixed brace supporting the second moveable brace.
4. The propulsion device of claim 3, wherein the rail is configurable to vertically move while remaining stationary horizontally.
5. The propulsion device of claim 1, further comprising a cocking mechanism.
6. The propulsion device of claim 1, wherein the propulsion device has a width of 12 inches or less.
7. The propulsion device of claim 1, further comprising a trigger assembly.
8. The propulsion device of claim 1, wherein the at least one forward pulley comprises a first forward pulley, the device further comprising a second forward pulley.
9. The propulsion device of claim 1, wherein the forward spring member comprises a first forward spring member and the rearward spring member comprises a first rearward spring member, the device further comprising:
- a second forward spring member; and
- a second rearward spring member.
10. The propulsion device of claim 9, wherein the first and second forward spring members and the first and second rearward spring members are combined in parallel banks, wherein a first one of the parallel banks engages the first moveable pulley block and a second one of the parallel banks engages the second movable pulley block.
11. A propulsion device for propelling a projectile therefrom, comprising:
- an elongated member having a proximal fixed base and a distal fixed base;
- a forward spring member attached at a distal end thereof to the distal fixed base;
- a distal moveable pulley block attached to a proximal end of the forward spring member;
- at least a first and second distal pulley spaced apart and disposed on the distal moveable pulley block;
- a rearward spring member attached at a proximal end thereof to the proximal fixed base;
- a proximal moveable pulley block attached to a distal end of the rearward spring member;
- at least one proximal pulley disposed on the proximal moveable pulley block; and
- a launching cord spanning between the at least one proximal pulley and the first and second distal pulleys.
12. The propulsion device of claim 11, wherein the launching cord is attached at a first end to the proximal moveable pulley block and extends about the first distal pulley, returns to the at least one proximal pulley, extends back to the first distal pulley, continues to the second distal pulley, extends to the at least one proximal pulley, back to the second distal pulley, and terminates at a second end attached to the proximal moveable pulley block.
13. The propulsion device of claim 12, wherein at least one of the first end and the second end of the launching cord is attached to an adjustment mechanism to adjust a length of the launching cord.
14. The propulsion device of claim 11, wherein a launch cord center is disposed between the first and second distal pulleys, wherein the launch cord center is configured to receive a portion of one end of the projectile, wherein the launch cord center is moved proximally to achieve a cocked configuration.
15. The propulsion device of claim 11, further comprising a passive safety mechanism configured to prevent unintentional discharge of the projectile when the propulsion system is in a cocked configuration.
16. The propulsion device of claim 11, further comprising:
- a distal moveable brace interconnecting a distal end of the forward spring with the distal fixed brace, the distal moveable brace permitting movement between the distal end of the forward spring and the distal fixed brace; and
- a proximal moveable brace interconnecting a proximal end of the rearward spring with the proximal fixed brace, the proximal moveable brace permitting movement between the proximal end of the rearward spring and the proximal fixed brace.
17. The propulsion device of claim 11, further comprising an adjustable over-molded center rail configured to support the projectile, the adjustable over-molded center rail running along a length of the rail and being adjustable to adjust the position of the projectile relative to the rail.
18. The propulsion device of claim 11, further comprising a launching cord catch operable to secure the launching cord in a cocked configuration when the projectile is absent, thereby preventing dry-firing of the propulsion system.
19. The propulsion device of claim 11, further comprising a foot claw resiliently extendable from the distal end of the rail.
20. A propulsion device, comprising:
- a rail comprising a proximal fixed base and a distal fixed base;
- a forward spring member attached at a distal end thereof to the distal fixed base;
- a distal moveable pulley block attached to a proximal end of the forward spring member;
- at least a first and second distal pulley spaced apart and disposed on the distal moveable pulley block;
- at rearward spring member attached at a proximal end thereof to the proximal fixed base;
- a proximal moveable pulley block attached to a distal end of the rearward spring member;
- at least one proximal pulley disposed on the proximal moveable pulley block; and
- a launching cord spanning between the at least one proximal pulley and the first and second distal pulleys, wherein
- when the launching cord is pulled proximally from a launching cord center region formed between the first and second distal pulleys, a first force is exerted on the distal moveable pulley block by the forward spring member and a second force is exerted on the proximal moveable pulley block by the rearward spring member; and
- a quantity of the proximal pulleys, a quantity of the distal pulleys, a configuration of the launching cord, and a spring constant of the rearward and forward spring members are chosen to substantially balance the first force and the second force.
21. The propulsion device of claim 20, wherein the launching cord is attached at the first end to the proximal moveable pulley block and extends about the first distal pulley, returns to the at least one proximal pulley, extends back to the first distal pulley, continues to the second distal pulley, extends to the at least one proximal pulley, back to the second distal pulley, and terminates at the second end attached to the proximal moveable pulley block.
22. The propulsion device of claim 20, wherein:
- the forward spring includes at least one set of forward springs, the at least one set including a first forward spring and a second forward spring, the first and second forward springs being disposed on opposite sides of the rail; and
- the rearward spring includes at least one set of rearward springs, the at least one set including a first rearward spring and a second rearward spring, the first and second rearward springs being disposed on opposite sides of the rail.
Type: Application
Filed: Aug 17, 2015
Publication Date: Dec 10, 2015
Applicant: SERPENT RURAL SPORTS LLC (LOS GATOS, CA)
Inventors: JONATHAN C. POLANICH (LOS GATOS, CA), JAMES T. BOND (SANTA ROSA, CA)
Application Number: 14/828,047